[custom channels]: generate unique script keys for HTLCs #3497

Job	Run time
Format check	26s
Compilation check	49s
Docker build check	3m 35s
cross compilation	4m 34s
run itests	9m 28s
run itests postgres	17m 48s
Lint check	2m 46s
migration version check	11s
go mod check	23s
RPC check	1m 15s
Sqlc check	2m 50s
sample configuration check	37s
test vector check	44s
run LiT tests	17m 31s
run unit tests (unit-race)	11m 36s
run unit tests (unit-cover)	2m 57s
run unit tests (unit dbbackend=postgres)	6m 15s
finish	2s
	1h 23m 47s

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